import java.io.*;
class MAKERANDOM
{
	public static void main(String[] args)throws IOException
	{
		BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
		String string1;

		int num1, num2, num3, temp=0, sum=0;
		num1=Integer.parseInt(args[0]);
		num2=Integer.parseInt(args[1]);

		if(num1>num2)
		{
			for(num2=0;num2<=num1;num2++)
			{
				sum=sum+num2;
			}
		}
		else if(num1<num2)
		{
			for(num1=0;num1<=num2;num1++)
			{
				sum=sum+num1;
			}
		}
		else
			sum=num1+num2;

		System.out.print("wjdtnrkqt dlqfur : ");
		string1=stdin.readLine();
		num3=Integer.parseInt(string1);

		temp=sum-num3;

		System.out.println("rufrhksms " + temp);
	}
}
